PERITONEAL METASTATIC DISEASES
Sommaire
Peritoneal carcinomatosis of stomach cancers.
Synonyms:
Tumor ascites from gastric cancer, peritoneal metastases from stomach cancer, or stage 4 stomach cancer.
Epidemiology:
Stomach cancer affects nearly 6,500 people per year in France. The diagnosis is usually made after the age of 40. Stage 4 stomach cancer corresponds to a metastatic stage that can mainly affect the liver, deep lymph nodes, lungs, or peritoneum, either in isolation or in several of these organs. The annual incidence of peritoneal carcinomatosis or peritoneal metastases of gastric origin is estimated at between 1,000 and 2,000 cases per year.
Clinical description:
Carcinosis may be present at the initial diagnosis of the disease, i.e., identified at the same time as stomach cancer, which is known as synchronous disease. The other case is the discovery of carcinosis in the form of a recurrence of stomach cancer that had been operated on (known as metachronous disease).
Symptoms:
In some cases, there are no clinical signs and no abnormalities are visible on the scan. In these specific cases, carcinosis is discovered during exploratory laparoscopy before starting preoperative chemotherapy, or during surgery to remove the stomach cancer. Conversely, in other cases there is abdominal pain, weight loss, digestive problems, vomiting, or ascites, which may be clinical signs of more extensive carcinosis.
Etiology:
For some patients, peritoneal carcinomatosis is secondary to either a genetic predisposition that promotes the development of stomach cancer (which is very rare), potential exposure to environmental pollutants, or bacterial infection with Helicobacter pylori. In other cases, gastric carcinosis is secondary to the progression of stomach cancer, which releases tumor cells into the abdominal cavity: cancer perforation, involvement of its last layer (T4 tumor), associated ulcer, for example.
Diagnostic method:
The diagnosis of stomach cancer is based on a biopsy during a gastric endoscopy. The diagnosis of carcinosis is based on imaging tests, such as ultrasound and thoracoabdominal-pelvic CT scan. The diagnosis of carcinomatosis is confirmed by pathological examination of a biopsy, which can be obtained by laparoscopy or during a CT-guided puncture. The extent of carcinomatosis is determined during laparoscopy by calculating the PCI score (peritoneal cancer index or Sugarbaker score).
Differential diagnosis:
It must rule out peritoneal carcinomatosis secondary to other tumors (colon, appendix, small intestine, etc.) and other rare tumors of the peritoneum.
Treatment:
Treatment is multidisciplinary, involving oncologists for the administration of intravenous chemotherapy and surgeons to perform surgery at a “carcinosis surgery center of expertise.” The treatment sequence will depend on many factors and will be proposed, discussed, and validated during a dedicated meeting with these specialists (multidisciplinary team meeting).
Intravenous chemotherapy is always performed to control the disease, and immunotherapy is possible for certain tumors depending on their biological analysis. PIPAC (pressurized intraperitoneal chemotherapy or pressurized intraperitoneal aerosol chemotherapy – a promising therapeutic innovation) may be proposed and is currently being evaluated. Surgery for peritoneal carcinomatosis depends on several factors, including the extent of the disease and therefore the complete removal of nodules. Thus, when complete resection surgery (gastrectomy and complete cytoreduction: visceral resections and peritonectomy) is possible, it may be offered to selected patients after validation by the multidisciplinary team, including oncologists and surgeons. Finally, this complete surgery combined with hyperthermic intraperitoneal chemotherapy (HIPEC), followed by intravenous chemotherapy, can only be considered for young patients in good general health with limited peritoneal carcinomatosis. Nevertheless, the role of HIPEC is highly debated, but it is an option that can be discussed.
Prognosis:
Peritoneal carcinomatosis of gastric origin is a serious disease, and recurrence after total removal of the tumor and carcinomatosis is common.
AMARAPE Scientific Advisory Board chaired by Professor Olivier Glehen (September 2025)
Peritoneal carcinomatosis of colon cancer
Synonyms:
Tumor ascites of colon cancer, peritoneal metastases of colon or rectal cancer, stage 4 colon cancer.
Epidemiology:
Colon cancer affects nearly 50,000 people per year in France. The diagnosis is usually made after the age of 40. Stage 4 colon cancer corresponds to a metastatic stage that can mainly affect the liver, lungs, or peritoneum, either in isolation or in each of the three organs targeted by the metastases. The annual incidence of colonic carcinosis is estimated at between 2,000 and 5,000 cases per year.
Clinical description:
Carcinosis may be present at the initial diagnosis of the disease, identified at the same time as colon cancer, as a synchronous disease, or later as a recurrence (metachronous disease). In some cases, there are no clinical signs and no abnormalities are visible on the CT scan; carcinosis is discovered during colon cancer surgery. Conversely, in other cases there is abdominal pain, weight loss, urinary symptoms, constipation, vomiting, or ascites, which are less common clinical signs.
Etiology:
Some patients have a genetic predisposition that increases their risk of developing colon cancer, such as familial polyposis or Lynch syndrome. In some cases, the colon tumor has perforated into the peritoneal cavity, which explains the occurrence of carcinosis, but this is not always the case.
Diagnostic method:
The diagnosis of colon cancer is based on a biopsy during a colonoscopy. The diagnosis of carcinomatosis is based on imaging tests, such as ultrasound and thoracoabdominal-pelvic CT scan. The diagnosis of carcinomatosis is confirmed by pathological examination of a biopsy, which can be obtained by laparoscopy or during a CT-guided biopsy. The extent of carcinomatosis is determined during laparoscopy by calculating the PCI score (or Sugarbaker score).
Differential diagnosis:
It must rule out peritoneal carcinomatosis secondary to other tumors (stomach, appendix, small intestine, etc.) and other rare tumors of the peritoneum.
Treatment:
Treatment is multidisciplinary, involving intravenous chemotherapy, and surgery must be performed at a center with expertise in carcinomatosis surgery. The treatment sequence will depend on many factors and will be proposed after a multidisciplinary team meeting.
Intravenous chemotherapy is always used to control the disease, and immunotherapy is possible for certain tumors depending on their biological analysis. When complete surgical resection and removal of the carcinoma is possible, this is the best option for a cure. Complete cytoreductive surgery (visceral resection and peritonectomy) combined with hyperthermic intraperitoneal chemotherapy (HIPEC), followed by intravenous chemotherapy, is a treatment protocol that can only be considered for young patients in good general health. The role of HIPEC has not been demonstrated by robust studies, but it is an option that should be discussed.
Prognosis:
Peritoneal carcinomatosis of colonic origin is a serious disease and recurrence after complete tumor removal is possible. After combined treatment (complete cytoreductive surgery and HIPEC) of colonic carcinomatosis, the 5-year survival rate reaches 40% for patients treated by a specialist center, but only 15% of patients will be disease-free at 5 years.
AMARAPE Scientific Council chaired by Professor Olivier Glehen (September 2025)